<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8"/>
<title></title>
<style type="text/css">
#p1{font-weight:lighter;}
#p2{font-weight:normal;}
#p3{font-weight:bold;}
#p4{font-weight:bolder;}
</style>
</head><body>
    <p id="p1">字体粗细为:lighter</p>
<p id="p2">字体粗细为:normal</p>
<p íd="p3">字体粗细为:bold</p>
<p id="p4">字体粗细为:bolder </p></body>
</html>